1. Field of the Invention
The present invention relates to a centrifuge, and more particularly, a centrifuge which continuously performs centrifugal separation on a sample.
2. Description of the Related Art
Centrifuges are used for separating particles which do not, or do not easily, settle out in a normal gravitational field. Particles separated by centrifuges include viruses and fungus bodies which are necessary materials for producing medicines and vaccines. In a production process of medicines and vaccines, continuous flow centrifuges which can continuously separate and refine materials are used.
Continuous flow centrifuges have a face seal which abuts a rotation shaft of a rotor. The face seal is supported by a spring so as to contact the rotation shaft with a constant pressure. In order to cool down the face seal which generates heat due to friction with the rotation shaft, a coolant is circulated around the periphery of the face seal.
Unexamined Japanese Patent Application KOKAI Publication No. 2006-247610 discloses a continuous flow centrifuge which has a face seal held by two kinds of O-rings formed of different materials. According to such a continuous flow centrifuge, it is possible to prevent a contamination of a sample with a coolant due to a seal defect caused by a swelling of an O-ring.
The face seal has a lifetime and needs to be replaced, in general, after about 40 to 50 hours of operation, even though it is cooled down by a coolant. When the face seal is continuously used beyond its lifetime, a sealing property between the rotation shaft of the rotor and the face seal is lost, so that it becomes difficult to isolate a sample from the coolant. Accordingly, the sample may be contaminated by the coolant, and may become improper to use.